Not sure what you mean by celebrate solitude. Most mantras point you back to your true nature. There is "om jyotir aham' (I am the light); 'So hum' (I am that). Then there are mahavakyas which can be used as mantras: e.g., Aham Brahmasmi (I am Brahman).

I would love to hear what mantras people use.

Are mantras thought suppression?

I think of mantras as thought replacement. That is, they replace the recursive thinking with something useful (i.e., a pointer to the self).

Not sure what you mean by celebrate solitude. Most mantras point you back to your true nature. There is "om jyotir aham' (I am the light); 'So hum' (I am that). Then there are mahavakyas which can be used as mantras: e.g., Aham Brahmasmi (I am Brahman).

You focus your attention on one object (the mantra). This leads, when practised very intensive, to ceasation of other thought. But it's more effective when the mantra means something for you.
Doing it mechanically like a robot, doesn't do much. In the bhakti tradition it is all about love. Chanting a mantra, has to come from the heart. It's like a prayer.